Filters

[djkarn105]

So aside from the standard ND, UV and polarizing filters, are there any filters you guys would reccomend? I have a warming filter that came with a lens I got off of ebay that makes skies look nice and I'm thinking a star filter would be pretty useful on music video shoots. Any other filters you guys regularly use?

 

[KeithAndrews.TV]

The general consensus is to shoot clean and effect in post. You have much more control over the image in the edit, and shooting without filtration allows you more flexibility say you change your mind with the way you want something to look. It's also a heck of a lot cheaper to buy software which can essentially do the same thing.

The exception to this would be any filters that help to maintain a certain aperture, or shutter rate, "ND, or ND Grads," or a special effects filter like a "Star" you mentioned. Although you could add a star effect in post, it would be advantageous and a whole lot quicker to simply use the filter while you are shooting.

Another great filter to keep on hand would be a "Polarizer." This does help control exposure, but is mainly intended to reduce glare. This filter is especially useful in controlling highlights as well, which is the achilles heel of digital video.

Don't waste your money on color grads, or promist filters. The look you are able to achieve with these filters can be easily replicated with any modern NLE program, or filter software.

 

[ydgmdlu]

Don't waste your money on color grads, or promist filters. The look you are able to achieve with these filters can be easily replicated with any modern NLE program, or filter software.

Actually, diffusion filters like ProMist can be useful because they can help reduce moire and aliasing artifacts on the Canon DSLRs. Also, different diffusion and soft focus filters have subtly different effects, and you can't easily replicate them all in post. Yes, you can apply a generic "soft focus" effect in software, but what if you specifically want the look of a Black ProMist? It's just not exactly the same as a generic soft focus.

 

[djkarn105]

Ah yes, forgot CPL, got one of those too.

Seems like a subtle softening filter might be a good idea in moire situations. Also, it takes 30 seconds to put on a soft filter and 30 minutes to render it.

The reason you would not want to use a star filter is that if you're shooting a subject with a highlight that's creating a star and they pass behind something the star goes away with them. This is very much NOT the case in post (and a HUGE pita to replicate).

 

[KeithAndrews.TV]

I don't agree with the use of a diffusion filter to soften the effects of moire, simply because you are affecting the entire image, not just the area that is exhibiting the moire. The filter does not eliminate the moire, just masks it. I would much rather apply a digital filter, or use a plugin where I can isolate the region that I am effecting.

As far as render times are concerned, that's all going to be dependent upon the system you are using. Some NLE's, when using the right software package and application, can perform the digital effects in almost realtime, if not realtime. Considering you are always going to be exporting whatever you import, the added time to render a digital effect may be negligible.

I would take a look at Tiffen's Dfx software package before making a decision about purchasing an actual hard copy of a filter. When you have guys like Still Motion using the software on same day edits, you know it can't be too much of a burden to use.

 

[ydgmdlu]

I don't agree with the use of a diffusion filter to soften the effects of moire, simply because you are affecting the entire image, not just the area that is exhibiting the moire. The filter does not eliminate the moire, just masks it. I would much rather apply a digital filter, or use a plugin where I can isolate the region that I am effecting.

How do you decrease or eliminate moire in post?

The point of using an optical filter is to correct the issue at the source. Moire is an aliasing artifact caused by a combination of an inadequately-tuned optical low-pass filter and an inferior image down-scaling method. Compensating for the optical low-pass is the best way to combat moire. It's how the Caprock Anti-Moire filter works.

A soft focus or diffusion filter doesn't "mask" moire. (How's that even possible? What is "masking," and how is it different from actually reducing the moire?) The idea is to reduce the image detail being projected onto the sensor, thus reducing the amount of moire aliasing when the image is down-scaled. Once the image is recorded, the moire is already burned into the image. Whatever you do in post can't possibly take it away, only decrease how perceptible it is.

The best way to reduce or eliminate moire is by preventing it from happening in the first place, either by avoiding subjects prone to it or by using an optical filter on the lens. The Caprock is the best because it was specifically designed to do it, while a soft focus filter does it as a side effect of its main effect. But the Caprock isn't cheap, which might be reason enough for frugal users to try soft focus instead.